rustdoc_json: improve handling of generic args #142502

nnethercote · 2025-06-14T12:46:25Z

This PR fixes some inconsistencies and inefficiencies in how generic args are handled by rustdoc-json-types.

rustbot · 2025-06-14T12:46:30Z

rustdoc-json-types is a public (although nightly-only) API. If possible, consider changing src/librustdoc/json/conversions.rs; otherwise, make sure you bump the FORMAT_VERSION constant.

cc @CraftSpider, @aDotInTheVoid, @Enselic, @obi1kenobi

nnethercote · 2025-06-15T00:56:03Z

Local measurements indicate some sub-1% instruction count improvements, and some max-rss improvements of up to 2%, in rustdoc-json perf.

bors · 2025-06-15T03:28:55Z

☔ The latest upstream changes (presumably #142335) made this pull request unmergeable. Please resolve the merge conflicts.

aDotInTheVoid

Behavioral changes make sense, but all of them needs tests.

They live in tests/rustdoc-json. Sadly, I've not finished the docs for it yet (rust-lang/rustc-dev-guide#2422), but there's a draft here

type/generic_default.rs and gats.rs are probably good examples

src/librustdoc/json/conversions.rs

src/rustdoc-json-types/lib.rs

rustbot · 2025-06-16T00:10:18Z

These commits modify tests/rustdoc-json.
rustdoc-json is a public (but unstable) interface.

Please ensure that if you've changed the output:

It's intentional.
The FORMAT_VERSION in src/librustdoc-json-types is bumped if necessary.

cc @aDotInTheVoid, @obi1kenobi

nnethercote · 2025-06-16T00:11:18Z

I added a test as a separate commit early in the sequence, so the changes to GenericArgs are visible in the changes to the test.

@rustbot ready

aDotInTheVoid · 2025-06-16T23:01:55Z

r=me after #142601 lands, and then this gets rebased to change the "Latest Change" comment.

bors · 2025-06-17T22:07:48Z

☔ The latest upstream changes (presumably #142613) made this pull request unmergeable. Please resolve the merge conflicts.

nnethercote · 2025-06-17T23:11:58Z

I fixed the conflicts and updated the FORMAT_VERSION message.

@bors r=aDotInTheVoid

bors · 2025-06-17T23:12:01Z

📌 Commit 81a2aec has been approved by aDotInTheVoid

It is now in the queue for this repository.

…gs, r=aDotInTheVoid rustdoc_json: improve handling of generic args This PR fixes some inconsistencies and inefficiencies in how generic args are handled by rustdoc-json-types. r? `@aDotInTheVoid`

Rollup of 10 pull requests Successful merges: - #135656 (Add `-Z hint-mostly-unused` to tell rustc that most of a crate will go unused) - #138237 (Get rid of `EscapeDebugInner`.) - #140772 ({aarch64,x86_64}-pc-windows-gnullvm: build host tools) - #140774 (Affirm `-Cforce-frame-pointers=off` does not override) - #141610 (Stabilize `feature(generic_arg_infer)`) - #141864 (Handle win32 separator for cygwin paths) - #142384 (Bringing `rustc_rayon_core` in tree as `rustc_thread_pool`) - #142502 (rustdoc_json: improve handling of generic args) - #142571 (Reason about borrowed classes in CopyProp.) - #142591 (Add spawn APIs for BootstrapCommand to support deferred command execution) r? `@ghost` `@rustbot` modify labels: rollup

bors · 2025-06-18T10:20:12Z

☔ The latest upstream changes (presumably #138165) made this pull request unmergeable. Please resolve the merge conflicts.

rust-bors · 2025-06-18T14:03:00Z

⌛ Trying commit a172d78 with merge 6a7fca5…

To cancel the try build, run the command @bors2 try cancel.

rustdoc_json: improve handling of generic args This PR fixes some inconsistencies and inefficiencies in how generic args are handled by rustdoc-json-types. r? `@aDotInTheVoid` try-job: x86_64-mingw-2

rust-bors · 2025-06-18T15:43:29Z

💔 Test failed

CI ❌

nnethercote · 2025-06-18T21:31:08Z

There was a failure in the new tests for the type sizes, likely caused by rustc_randomized_layout. I will move those checks from the test into static assertions in src/librustdoc/json/mod.rs. This is much better: the assertions are static so you get a compile-time error (earlier) on failure; they can handle rustc_randomized_layout because they use static_assert_size; they are done in the same way as size assertion all throughout the rest of the codebase. I should have done them that way in the first place.

nnethercote · 2025-06-18T22:27:31Z

@bors2 try jobs=x86_64-mingw-2

rust-bors · 2025-06-18T22:27:34Z

⌛ Trying commit 2f916c5 with merge 53e44a5…

To cancel the try build, run the command @bors2 try cancel.

rustdoc_json: improve handling of generic args This PR fixes some inconsistencies and inefficiencies in how generic args are handled by rustdoc-json-types. r? `@aDotInTheVoid` try-job: x86_64-mingw-2

rust-bors · 2025-06-18T23:29:54Z

💔 Test failed

CI ❌

A lot of these are large! Lots of room for improvement in the future.

A path without generic args, like `Reader`, currently has JSON produced like this: ``` {"path":"Reader","id":286,"args":{"angle_bracketed":{"args":[],"constraints":[]}}} ``` Even though `types::Path::args` is `Option` and allows for "no args", instead it gets represented as "empty args". (More like `Reader<>` than `Reader`.) This is due to a problem in `clean::Path::from_clean`. It only produces `None` if the path is an empty string. This commit changes it to also produce `None` if there are no generic args. The example above becomes: ``` {"path":"Reader","id":286,"args":null} ``` I looked at a few examples and saw this reduce the size of the JSON output by 3-9%. The commit also adds an assertion that non-final segments don't have any generics; something the old code was implicitly relying on. Note: the original sin here is that `clean::PathSegment::args` is not an `Option`, unlike `{ast,hir}::PathSegment::args`. I want to fix that, but it can be done separately.

As per the previous commit, generic args here can only appear on the final segment. So make the comments obey that constraint.

They show up in three places: once as `Option<Box<GenericArgs>>`, once as `Box<GenericArgs>`, and once as `GenericArgs`. The first option is best. It is more compact because generic args are often missing. This commit changes the latter two to the former. Example output, before and after, for the `AssocItemConstraint` change: ``` {"name":"Offset","args":{"angle_bracketed":{"args":[],"constraints":[]}},"binding":{...}} {"name":"Offset","args":null,"binding":{...}} ``` Example output, before and after, for the `Type::QualifiedPath` change: ``` {"qualified_path":{"name":"Offset","args":{"angle_bracketed":{"args":[],"constraints":[]}}, ...}} {"qualified_path":{"name":"Offset","args":null, ...}} ``` This reduces JSON output size, but not by much (e.g. 0.5%), because `AssocItemConstraint` and `Type::QualifiedPath` are uncommon.

nnethercote · 2025-06-19T03:18:22Z

There was a failure in the new tests for the type sizes, likely caused by rustc_randomized_layout

Turns out it was because PathBuf is different sizes on different OSes. (The switch to static assertions was still a good one.) I have adjusted the Item size assertion accordingly.

@bors try

bors · 2025-06-19T03:19:33Z

⌛ Trying commit 91818ba with merge 93c2176...

rustdoc_json: improve handling of generic args This PR fixes some inconsistencies and inefficiencies in how generic args are handled by rustdoc-json-types. r? `@aDotInTheVoid`

Kobzol · 2025-06-19T04:36:24Z

@bors2 try jobs=x86_64-mingw-2

rust-bors · 2025-06-19T04:36:27Z

⌛ Trying commit 91818ba with merge 31df07f…

To cancel the try build, run the command @bors2 try cancel.

rustdoc_json: improve handling of generic args This PR fixes some inconsistencies and inefficiencies in how generic args are handled by rustdoc-json-types. r? `@aDotInTheVoid` try-job: x86_64-mingw-2

bors · 2025-06-19T05:49:53Z

☀️ Try build successful - checks-actions
Build commit: 93c2176 (93c2176d5e5c4a5fce647f345a930c72a017e9a2)

rust-bors · 2025-06-19T06:42:22Z

☀️ Try build successful (CI)
Build commit: 31df07f (31df07f8fae14bfe655d5749fecd8e13105cd6fe, parent: d1d8e386c5e84c4ba857f56c3291f73c27e2d62a)

nnethercote · 2025-06-19T08:35:13Z

@bors r=aDotInTheVoid

bors · 2025-06-19T08:35:15Z

📌 Commit 91818ba has been approved by aDotInTheVoid

It is now in the queue for this repository.

…gs, r=aDotInTheVoid rustdoc_json: improve handling of generic args This PR fixes some inconsistencies and inefficiencies in how generic args are handled by rustdoc-json-types. r? `@aDotInTheVoid`

Rollup of 6 pull requests Successful merges: - #141990 (Implement send_signal for unix child processes) - #142331 (Add `trim_prefix` and `trim_suffix` methods for both `slice` and `str` types.) - #142502 (rustdoc_json: improve handling of generic args) - #142629 (Add config builder for bootstrap tests) - #142687 (Reduce uses of `hir_crate`.) - #142714 (add comment to `src/bootstrap/build.rs`) r? `@ghost` `@rustbot` modify labels: rollup

rustbot assigned aDotInTheVoid Jun 14, 2025

rustbot added A-rustdoc-json Area: Rustdoc JSON backend S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-rustdoc Relevant to the rustdoc team, which will review and decide on the PR/issue. labels Jun 14, 2025

nnethercote force-pushed the rustdoc-json-GenericArgs branch from f232c4e to 27eee69 Compare June 15, 2025 04:17

aDotInTheVoid reviewed Jun 15, 2025

View reviewed changes

src/librustdoc/json/conversions.rs Show resolved Hide resolved

src/rustdoc-json-types/lib.rs Show resolved Hide resolved

src/rustdoc-json-types/lib.rs Show resolved Hide resolved

aDotInTheVoid added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jun 15, 2025

nnethercote force-pushed the rustdoc-json-GenericArgs branch from 27eee69 to f3c20ca Compare June 16, 2025 00:10

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jun 16, 2025

aDotInTheVoid mentioned this pull request Jun 16, 2025

Rewrite inline attribute parser to use new infrastructure and improve diagnostics for all parsed attributes #138165

Merged

nnethercote force-pushed the rustdoc-json-GenericArgs branch from f3c20ca to 81a2aec Compare June 17, 2025 23:10

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jun 17, 2025

jhpratt mentioned this pull request Jun 18, 2025

Rollup of 10 pull requests #142656

Closed

bors added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Jun 18, 2025

nnethercote force-pushed the rustdoc-json-GenericArgs branch from a172d78 to 2f916c5 Compare June 18, 2025 22:21

nnethercote added 5 commits June 19, 2025 13:16

rustdoc_json: Add static asserts for the size of important types.

0a4507c

A lot of these are large! Lots of room for improvement in the future.

rustdoc_json: Add a test for some GenericArgs cases.

82f8220

Fix some comments.

dba34b3

As per the previous commit, generic args here can only appear on the final segment. So make the comments obey that constraint.

nnethercote force-pushed the rustdoc-json-GenericArgs branch from 2f916c5 to 91818ba Compare June 19, 2025 03:17

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jun 19, 2025

Kobzol mentioned this pull request Jun 19, 2025

Rollup of 6 pull requests #142719

Closed

rustdoc_json: improve handling of generic args #142502

Are you sure you want to change the base?

rustdoc_json: improve handling of generic args #142502

Conversation

nnethercote commented Jun 14, 2025

Uh oh!

rustbot commented Jun 14, 2025

Uh oh!

nnethercote commented Jun 15, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

bors commented Jun 15, 2025

Uh oh!

aDotInTheVoid left a comment

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Uh oh!

Uh oh!

rustbot commented Jun 16, 2025

Uh oh!

nnethercote commented Jun 16, 2025

Uh oh!

aDotInTheVoid commented Jun 16, 2025

Uh oh!

bors commented Jun 17, 2025

Uh oh!

nnethercote commented Jun 17, 2025

Uh oh!

bors commented Jun 17, 2025

Uh oh!

bors commented Jun 18, 2025

Uh oh!

rust-bors bot commented Jun 18, 2025

Uh oh!

rust-bors bot commented Jun 18, 2025

Uh oh!

nnethercote commented Jun 18, 2025

Uh oh!

nnethercote commented Jun 18, 2025

Uh oh!

rust-bors bot commented Jun 18, 2025

Uh oh!

rust-bors bot commented Jun 18, 2025

Uh oh!

nnethercote commented Jun 19, 2025

Uh oh!

bors commented Jun 19, 2025

Uh oh!

Kobzol commented Jun 19, 2025

Uh oh!

rust-bors bot commented Jun 19, 2025

Uh oh!

bors commented Jun 19, 2025

Uh oh!

rust-bors bot commented Jun 19, 2025

Uh oh!

nnethercote commented Jun 19, 2025

Uh oh!

bors commented Jun 19, 2025

Uh oh!

Uh oh!

nnethercote commented Jun 15, 2025 •

edited

Loading